Activated transcription factor nuclear factor-kappa B is present in the atherosclerotic lesion

Nuclear factor-kappaB transcription factor decoy treatment inhibits graft coronary artery disease after cardiac transplantation in rodents

BACKGROUND

Nuclear factor-kappaB (NF-kappaB) is a transcription factor that upregulates adhesion molecules ICAM-1, VCAM-1, and ELAM-1. We hypothesized the use of ex vivo pressure-mediated delivery of transcription factor decoys (TFD) to NF-kappaB binding sites would decrease expression of adhesion molecules, and decrease reperfusion injury, acute rejection, and graft coronary artery disease (GCAD) in rat cardiac allografts.

METHODS

Heterotopic heart transplants were performed on donor hearts treated with saline, 10 mg/kg LPS, 160 micromol/L NF-kappaB TFD, or 160 micromol/L scrambled sequence (NF-SC) TFD for 45 min at 78 psi (6 atm). Transfection efficiency was determined with FITC-labeled TFD. Reverse transcription-PCR and immunohistochemistry was used to analyze adhesion molecule mRNA and protein expression, respectively. Apoptosis was measured with DNA fragmentation analysis. Reperfusion injury was assessed with cardiac edema, neutrophil infiltration, and histology. Acute rejection was determined by daily palpation. Allografts were assessed at POD 90 for the development of GCAD by computer-assisted image analysis to determine intimal:medial ratio and myointimal proliferation.

RESULTS

Hyperbaric pressure was an effective method of NF-kappaB TFD delivery (P<0.001 vs. controls). NF-kappaB TFD treatment led to decreased mRNA and protein expression of adhesion molecules. Treatment with NF-kappaB TFD led to a significant decrease in all reperfusion injury parameters compared to saline and NF-SC controls (P<0.01 vs. controls). Higher levels of apoptosis were seen in allografts treated with NF-kappaB TFD compared to control allografts. NF-kappaB TFD treatment prolonged allograft survival over saline and NF-SC controls (P<0.05). Myointimal proliferation and intimal:medial ratios in NF-kappaB TFD-treated allografts were significantly decreased compared to saline and NF-SC treatment (P<0.00001).

CONCLUSIONS

Ex vivo pressure-mediated delivery of NF-kappaB TFD is an effective method to block adhesion molcule expression and reperfusion injury in the immediate posttransplant period. Further, NF-kappaB TFD treatment prolongs allograft survival and decreases GCAD.

Induction of IkappaBalpha expression as a mechanism contributing to the anti-inflammatory activities of peroxisome proliferator-activated receptor-alpha activators

Chronic inflammation is a hallmark of degenerative diseases such as atherosclerosis. Peroxisome proliferator-activated receptors (PPARs) are transcription factors belonging to the nuclear receptor superfamily, which are expressed in the cells of the atherosclerosic lesion. PPARalpha ligands have been reported to exert anti-inflammatory activities in different cell types by antagonizing the transcriptional activity of NF-kappaB. In the present study, the influence of PPARalpha activators on the NF-kappaB signaling pathway was investigated. Our results show that fibrates, synthetic PPARalpha activators, induced the expression of the inhibitory protein IkappaBalpha in human aortic smooth muscle cells as well as in primary human hepatocytes, whereas neither IkappaB-kinase activity nor the degradation rate of IkappaBalpha were affected. Using PPARalpha-null mice, we demonstrated that fibrates induced IkappaBalpha in liver in vivo and that this action required PPARalpha. Furthermore, fibrate treatment induced IkappaBalpha protein expression in the cytoplasm and also enhanced IL-1beta-induced accumulation of IkappaBalpha protein in the nucleus. These actions of fibrates on IkappaBalpha expression were accompanied by a decrease in NF-kappaB DNA binding activity as demonstrated by electrophoretic mobility shift assays. Taken together, these data provide an additional molecular mechanism for the anti-inflammatory activity of PPARalpha agonists and reinforce their potential use in the treatment of inflammatory diseases.

NF-kappaB activation in response to toxical and therapeutical agents: role in inflammation and cancer treatment

The NF-kappaB transcription factor is ubiquitously expressed and controls the expression of a large number of genes. Experimental data clearly indicate that NF-kappaB is a major regulator of the inflammatory reaction by controlling the expression of pro-inflammatory molecules in response to cytokines, oxidative stress and infectious agents. We demonstrated that NF-kappaB activation by IL-1beta follows three distinct cell-specific pathways. Moreover, our studies indicated that in one model of inflammatory diseases, horse recurrent airway obstruction (RAO), the extent of NF-kappaB basal activity correlates with pulmonary dysfunction. Another role of NF-kappaB activity protects cancer cells against apoptosis and could participate in the resistance to cancer treatment. However, we did not observe any increased cytotoxicity after treatment with anticancer drugs or TNF-alpha of cells expressing a NF-kappaB inhibitor. Therefore, we can conclude that the inhibition of apoptosis by NF-kappaB is likely to be cell type and stimulus-dependent. Further studies are required to determine whether NF-kappaB could be a target for anticancer treatments.

Serotonin increases interleukin-6 synthesis in human vascular smooth muscle cells

BACKGROUND

Interleukin-6 (IL-6) is a key molecule in chronic inflammation and has been implicated in the progression of atherosclerosis. Serotonin (5-hydroxytryptamine; 5-HT) causes vascular contraction and proliferation, but its role in atherogenesis has not been clarified. We investigated the effects of 5-HT on IL-6 synthesis in human vascular smooth muscle cells (VSMCs).

METHODS AND RESULTS

IL-6 levels in the culture medium of VSMCs were determined by ELISA. IL-6 mRNA accumulation was determined by use of a Quantikine mRNA colorimetric quantification kit. NF-kappaB activation was tested by gel retardation assay. 5-HT induced IL-6 production by VSMCs in a time- and dose-dependent manner, with increased IL-6 mRNA accumulation and nuclear factor-kappaB activation. The effect of 5-HT on IL-6 production was significantly inhibited by the 5-HT(2) receptor antagonist ketanserin and the selective 5-HT(2A) receptor antagonist sarpogrelate. Conversely, the 5-HT(2) receptor agonist alpha-methyl-5-HT increased IL-6 production. The protein kinase C (PKC) inhibitor calphostin C, but not the protein kinase A inhibitor KT5720, suppressed 5-HT-induced IL-6 production. The effect of 5-HT was also abolished in PKC-depleted VSMCs after pretreatment with phorbol 12-myristate 13-acetate for 24 hours.

CONCLUSIONS

5-HT acts on 5-HT(2A) receptors and increases IL-6 synthesis in human VSMCs at least partially through a PKC-dependent pathway. These results suggested that 5-HT may contribute to inflammatory activation of the vessels during atherogenesis.

Inhibition of vascular smooth muscle cell proliferation by sodium salicylate mediated by upregulation of p21(Waf1) and p27(Kip1)

BACKGROUND

Salicylates may have direct vascular effects by mechanisms that are independent of platelet inhibition.

METHODS AND RESULTS

We investigated the effect of salicylates on vascular smooth muscle cell (SMC) proliferation in response to platelet-derived growth factor (PDGF) in vitro. Salicylate concentrations of 5 and 10 mmol/L inhibited serum- or PDGF-induced SMC cell count and [(3)H]thymidine incorporation by 62% and 81%, respectively. There was no evidence of cellular toxicity or apoptosis as determined by trypan blue exclusion and FACS analyses. Because cell cycle progression is regulated by hyperphosphorylation of the retinoblastoma (Rb) protein, we examined the effects of salicylate on Rb hyperphosphorylation. Treatment with salicylate, but not indomethacin, inhibited nuclear factor-kappaB activation and completely abolished Rb hyperphosphorylation in PDGF-treated SMCs. This effect was associated with a decrease in cyclin-dependent kinase (Cdk)-2 and, to a lesser extent, Cdk-6, but not Cdk-4 activity, without changes in Cdk-2, -4, and -6 and cyclin D and E protein levels. Because Cdk-2 activity is regulated by the Cdk inhibitors p21(Waf1) and p27(Kip1), we studied the effects of salicylate on p21(Waf1) and p27(Kip1) expression. Treatment with salicylate prevented PDGF-induced downregulation of p21(Waf1) and p27(Kip1) but not of the Cdk-4/-6 inhibitor p16(Ink4).

CONCLUSIONS

These findings indicate that high doses of salicylates inhibit SMC proliferation by cell cycle arrest at the G(1)-S phase and suggest a beneficial role for high-dose salicylates in the treatment of vascular proliferative disorders.

Overexpression of truncated IkappaBalpha induces TNF-alpha-dependent apoptosis in human vascular smooth muscle cells

Dysregulation of apoptosis is one of the likely underlying mechanisms of neointimal thickening, a disorder in which proinflammatory cytokines may influence the function of vascular smooth muscle cells (VSMCs) and contribute to atherogenesis. One of these cytokines, tumor necrosis factor-alpha (TNF-alpha), induces 2 possibly conflicting pathways, 1 leading to the activation of nuclear factor-kappaB (NF-kappaB) and the other leading to caspase-mediated apoptosis. We investigated whether specific inhibition of NF-kappaB affects TNF-alpha-dependent apoptosis in human VSMCs. To inhibit NF-kappaB activation specifically, we constructed a recombinant adenovirus vector expressing a truncated form of the inhibitor protein IkappaBalpha (AdexIkappaBDeltaN) that lacks the phosphorylation sites essential for activation of NF-kappaB. The IkappaBDeltaN was overexpressed by adenoviral infection and was resistant to stimulus-dependent degradation. Electromobility gel shift and luciferase assays demonstrated that overexpression of IkappaBDeltaN inhibited NF-kappaB activation induced by TNF-alpha or interleukin-1beta (IL-1beta). In cells overexpressing IkappaBDeltaN, TNF-alpha dramatically induced apoptosis, whereas IL-1beta had no effect. The induction was suppressed by treatment with a selective inhibitor of the caspase-3 family, Z-DEVD-fmk, and the overexpression of IkappaBDeltaN induced TNF-alpha-mediated caspase-3 and caspase-2 activity. These results indicate that overexpression of IkappaBDeltaN induces TNF-alpha-dependent apoptosis by efficient and specific suppression of NF-kappaB and upregulation of caspase-3 and caspase-2 activity in human VSMCs. Our findings suggest that adenovirus-mediated IkappaBDeltaN gene transfer may be useful in the treatment of disorders associated with inflammatory conditions, such as the response to vascular injury and atherosclerosis.

Implication of NF-kappaB in Helicobacter pylori-associated gastritis

OBJECTIVE

Transcription factor NF-kappaB plays a pivotal role in inflammatory responses by up-regulating mRNA expression of bioactive molecules such as chemokines and adhesion molecules. The present study was designed to elucidate the implication of NF-kappaB in Helicobacter pylori-associated gastritis (HAG).

METHODS

We examined 41 patients with HAG and 18 H. pylori-negative control subjects. Expression of activated NF-kappaB was studied in situ by immunohistochemistry using alpha-p65 mouse monoclonal antibody (alpha-p65 mAb), which recognizes activated NF-kappaB. To identify the cell types in which NF-kappaB was activated, we performed immunohistochemical analysis using antibodies against vascular endothelial cells, macrophages, and B and T lymphocytes. We also examined the colocalization of activated NF-kappaB with the of intercellular expression adhesion molecule-1 (ICAM-1) on endothelial cells. We measured the levels of NF-kappaB-dependent chemokines including interleukin-8 (IL-8) and monocyte chemoattractant protein-1 (MCP-1), regulated on activation normal T-cell expressed and secreted (RANTES) and macrophage inflammatory protein-1alpha (MIP-1alpha) in antral mucosa by ELISA (ELISA).

RESULTS

Activated NF-kappaB was detected in the nuclei of epithelial cells in antral mucosa, especially of patients with HAG. NF-kappaB positivity index (NF-kappaB PI), representing the percentages of epithelial cells with positive nuclear staining for activated NF-kappaB, was significantly higher in patients with HAG than in H. pylori-negative controls. NF-kappaB PI correlated significantly with histological scores of gastritis. Moreover, activated NF-kappaB was identified in the nuclei of vascular endothelial cells, macrophages, and B lymphocytes within the lamina propria in HAG. Colocalization of activated NF-kappaB with ICAM-1 expression in the same endothelial cells was demonstrated. The IL-8 levels significantly correlated with the NF-kappaB PI.

CONCLUSIONS

In addition to epithelial cells, macrophages, vascular endothelial cells, and B lymphocytes contained activated NF-kappaB. In these cells, activated NF-kappaB may be involved in the inflammation process in HAG through the up-regulation of chemokines or adhesion molecules.

Role of endocytosis in the transactivation of nuclear factor-kappaB by oxidized low-density lipoprotein

Oxidized low-density lipoprotein (oxLDL) has been shown to modulate transactivation by the peroxisome proliferator-activated receptor (PPAR)-gamma and by nuclear factor-kappaB (NF-kappaB). In the present study, the oxLDL signalling pathways involved in NF-kappaB transactivation were investigated by utilizing a reporter construct driven by three upstream NF-kappaB binding sites, and various pharmacological inhibitors. OxLDL and its constituent lysophophatidylcholine (lysoPC) induced a rapid and transient increase in intracellular calcium and stimulated NF-kappaB transactivation in resting RAW264.7 macrophage cells in an oxidation-dependent manner. NF-kappaB activation by oxLDL or lysoPC was inhibited by inhibitors of protein kinase C or by a chelator of intracellular calcium. Tyrosine kinase or phosphatidylinositol 3-kinase inhibitors did not block NF-kappaB transactivation. Furthermore, oxLDL-induced NF-kappaB activity was abolished by PPAR-gamma ligands. When the endocytosis of oxLDL was blocked by cytochalasin B, NF-kappaB transactivation by oxLDL was synergistically increased, while PPAR transactivation was blocked. These results suggest that oxLDL activates NF-kappaB in resting macrophages via protein kinase C- and/or calcium-dependent pathways, and that this does not involve the endocytic processing of oxLDL. The endocytosis-dependent activation of PPAR-gamma by oxLDL may function as a route of inactivation of the oxLDL-induced NF-kappaB signal.

Adiponectin, an adipocyte-derived plasma protein, inhibits endothelial NF-kappaB signaling through a cAMP-dependent pathway

BACKGROUND

Among the many adipocyte-derived endocrine factors, we found an adipocyte-derived plasma protein, adiponectin, that was decreased in obesity. We recently demonstrated that adiponectin inhibited tumor necrosis factor-alpha (TNF-alpha)-induced expression of endothelial adhesion molecules and that plasma adiponectin level was reduced in patients with coronary artery disease (CIRCULATION: 1999;100:2473-2476). However, the intracellular signal by which adiponectin suppressed adhesion molecule expression was not elucidated. The present study investigated the mechanism of modulation for endothelial function by adiponectin.

METHODS AND RESULTS

The interaction between adiponectin and human aortic endothelial cells (HAECs) was estimated by cell ELISA using biotinylated adiponectin. HAECs were preincubated for 18 hours with 50 microg/mL of adiponectin, then exposed to TNF-alpha (10 U/mL) or vehicle for the times indicated. NF-kappaB-DNA binding activity was determined by electrophoretic mobility shift assays. TNF-alpha-inducible phosphorylation signals were detected by immunoblotting. Adiponectin specifically bound to HAECs in a saturable manner and inhibited TNF-alpha-induced mRNA expression of monocyte adhesion molecules without affecting the interaction between TNF-alpha and its receptors. Adiponectin suppressed TNF-alpha-induced IkappaB-alpha phosphorylation and subsequent NF-kappaB activation without affecting other TNF-alpha-mediated phosphorylation signals, including Jun N-terminal kinase, p38 kinase, and Akt kinase. This inhibitory effect of adiponectin is accompanied by cAMP accumulation and is blocked by either adenylate cyclase inhibitor or protein kinase A (PKA) inhibitor.

CONCLUSIONS

These observations raise the possibility that adiponectin, which is naturally present in the blood stream, modulates the inflammatory response of endothelial cells through cross talk between cAMP-PKA and NF-kappaB signaling pathways.

Modulation of vascular cell activation, function, and apoptosis: role of antioxidants and nuclear factor-kappa B

The activity of NF-kappa B is critically involved in the inflammatory activation of endothelial cells and their adhesiveness and also appears to regulate apoptosis in SMC by coordinating antiapoptotic programs. The activity of NF-kappa B has been revealed within human atheromas or following angioplasty but not in undiseased arteries. Hence, the inhibition of NF-kappa B mobilization by antioxidative or anti-inflammatory agents or by adenoviral I kappa B alpha overexpression, as reviewed herein, may act in concert to suppress endothelial activation and to induce SMC apoptosis. This synergistic concept may be a vasoprotective approach to prevent atherogenesis and restenosis by attenuating inflammatory reactions and SMC proliferation in nascent and progressing atherosclerotic lesions, as well as in developing neointima formations following angioplasty.

Effects of alpha-tocopherol on ox-LDL-mediated degradation of IkappaB and apoptosis in cultured human coronary artery endothelial cells

Experimental studies have demonstrated that vitamin E (alpha-tocopherol) may provide significant cytoprotection during cell injury. In this study, we examined the effects of alpha-tocopherol on oxidized low-density lipoprotein (ox-LDL)-induced apoptosis in human coronary artery endothelial cells (HCAECs). In addition, we examined the activation of NF-kappaB pathway in this process. Cultured HCAECs were treated with ox-LDL for 24 h. Incubation of HCAECs with ox-LDL resulted in apoptosis of HCAECs in a concentration-dependent manner, as determined by TUNEL and DNA laddering. Ox-LDL degraded IkappaB and activated NF-kappaB in HCAECs, as determined by Western blot analysis. Treatment with alpha-tocopherol (10 and 50 microM) decreased ox-LDL-mediated apoptosis as well as degradation of IkappaB and activation of NF-kappaB in HCAECs. High concentration of alpha-tocopherol (50 microM) was more effective than the low concentration of alpha-tocopherol (10 microM). Thus, ox-LDL induces apoptosis of HCAECs, in concurrence with degradation of IkappaB and activation of NF-kappaB. Alpha-tocopherol markedly decreases ox-LDL-induced effects.

Angiotensin II induces gene transcription through cell-type-dependent effects on the nuclear factor-kappaB (NF-kappaB) transcription factor

The vasopressor octapeptide, angiotensin II (Ang II), exerts homeostatic responses in cardiovascular tissues, including the heart, blood vessel wall, adrenal cortex and liver (a major source of circulating plasma proteins). One of the effects of Ang II is to induce expression of regulatory, structural and cytokine genes that play important roles in long-term control of blood pressure, vascular remodeling, cardiac hypertrophy and inflammation. The identification of nuclear signaling pathways and target transcription factors has provide important insight into cellular responses and the spectrum of genes controlled by Ang II. Here we will review how Ang II activates the transcription factors, Activator Protein 1 (AP-1), Signal Transducer and Activator of Transcription (STATs), and Nuclear Factor-kappaB (NF-kappaB). NF-kappaB is of particular interest because it is an important mediator of resynthesis of the Ang II precursor, angiotensinogen AGT. Through this positive feedback loop, long-term changes in the activity of the renin angiotensin system occur. Although NF-kappaB is ubiquitously expressed, surprisingly the mechanism for Ang II-inducible NF-kappaB regulation differs between aortic smooth muscle cells (VSMCs) and hepatocytes. In VSMC, Ang II induces nuclear translocation of cytoplasmic transactivatory NF-kappaB proteins through proteolysis of its inhibitor, IkappaB. By contrast, in hepatocytes, Ang II induces large nuclear isoforms of NF-kappaB1 to bind DNA through a mechanism independent of changes in IkappaB turnover. NF-kappaB activation depends upon the activity of DAG-sensitive PKC isoforms and ROS signaling pathway. These observations indicate that significant differences exist in Ang II signaling depending upon cell-type involved and suggest the possibility that tissue-selective modulation of Ang II effects is possible in the cardiovascular system.

The role of CBP in estrogen receptor cross-talk with nuclear factor-kappaB in HepG2 cells

Functional interactions or cross-talk between ligand-activated nuclear receptors and the proinflammatory transcription factor nuclear factor-kappaB (NF-kappaB) may play a major role in ligand-mediated modification of diseases processes. In particular, the cardioprotective effects of estrogen replacement therapy are thought to be due in part to the ability of ligand-bound estrogen receptor (ER) to inhibit NF-kappaB function. In the current study 17beta-estradiol-bound ERalpha interfered with cytokine-induced activation of a NF-kappaB reporter in HepG2 cells. The estrogen metabolite, 17alpha-ethinyl estradiol, and the phytoestrogen, genistein, were also effective inhibitors of NF-kappaB activation, whereas tamoxifen, 4-hydroxytamoxifen, and raloxifene were inactive. This inhibition was reciprocal, as NF-kappaB interfered with the trans-activation properties of ERalpha. Ligand-bound ERalpha did not inhibit NF-kappaB binding to DNA, but it did decrease the histone acetyltransferase activity required for NF-kappaB transcriptional activity. Coexpression of the transcription coactivator CREB binding protein (CBP), but not steroid receptor coactivator 1a, reversed the ERalpha-mediated inhibition of NF-kappaB activity. Mammalian two-hybrid experiments also revealed that ligand-bound ERalpha can interact functionally with CBP-NF-kappaB complexes. We suggest that CBP targeting by ERalpha results in the inhibition of NF-kappaB and may occur through formation of transcriptionally inert multimeric complexes that are dependent upon the nature of the ERalpha ligand.

Red wine intake prevents nuclear factor-kappaB activation in peripheral blood mononuclear cells of healthy volunteers during postprandial lipemia

BACKGROUND

Several epidemiological studies have demonstrated the beneficial effect of red wine intake in reducing total and cardiovascular mortality. This effect has been attributed in part to its antioxidant properties. Because the monocytes/macrophages and the nuclear transcription factor kappaB (NF-kappaB) are implicated in the pathogenesis of atherosclerotic lesions, we examined the effect of red wine intake on the activation of NF-kappaB in peripheral blood mononuclear cells.

METHODS AND RESULTS

Sixteen healthy volunteers were studied 3 times each: after a moderate dose, a low dose, and no wine with a fat-enriched breakfast. Lipid profile and NF-kappaB activation (electrophoretic mobility shift assay) were examined in blood samples taken before and 3, 6, and 9 hours after wine intake. In addition, mononuclear cells were incubated with VLDL in the presence of some antioxidants (quercetin and alpha-tocopherol succinate) contained in red wine to study their effects on NF-kappaB activation. Subjects receiving a fat-enriched breakfast had increased NF-kappaB activation in peripheral blood mononuclear cells coinciding with the augmentation in total triglycerides and chylomicrons. Red wine intake prevented NF-kappaB activity even though it induced a certain increase in serum lipids, particularly VLDL, that did not increase after the fat ingestion alone. However, another form of alcohol intake (vodka) did not modify the NF-kappaB activation provided by postprandial lipemia. In cultured mononuclear cells, isolated human VLDL caused NF-kappaB activation in a time-dependent manner that did not occur in the presence of the red wine antioxidants quercetin and alpha-tocopherol.

CONCLUSIONS

Our results provide a new potential mechanism to explain the beneficial effects of red wine intake in the reduction of cardiovascular mortality.

Differential display identification of 40 genes with altered expression in activated human smooth muscle cells. Local expression in atherosclerotic lesions of smags, smooth muscle activation-specific genes

Detailed knowledge on the molecular and cellular mechanisms that control (re)-differentiation of vascular smooth muscle cells (SMCs) is critical to understanding the pathological processes underlying atherogenesis. We identified by differential display/reverse transcriptase-polymerase chain reaction 40 genes with altered expression in cultured SMCs upon stimulation with the conditioned medium of activated macrophages. This set of genes comprises 10 known genes and 30 novel genes, which we call "smags" (for smooth muscle activation-specific genes). To determine the in vivo significance of these (novel) genes in atherogenesis, we performed in situ hybridization experiments on vascular tissue. Specifically, FLICE (Fas-associated death domain-like interleukin-1beta-converting enzyme)-like inhibitory protein (FLIP) is expressed in neointimal SMCs as well as in lesion macrophages and endothelial cells, whereas the expression of the novel genes smag-63, smag-64, and smag-84 is restricted to neointimal SMCs. Characterization of full-length smag-64 cDNA revealed that it encodes a novel protein of 66 amino acids. smag-82 cDNA comprises the complete, unknown, 3'-untranslated region of fibroblast growth factor-5. Collectively, our results illustrate the complex changes of SMC gene expression that occur in response to stimulation with cytokines and growth factors secreted by activated macrophages. Moreover, we identified interesting candidate genes that may play a role in the differentiation of SMCs during atherogenesis.

The NF-kappa B signal transduction pathway in aortic endothelial cells is primed for activation in regions predisposed to atherosclerotic lesion formation

Atherosclerotic lesions form at distinct sites in the arterial tree, suggesting that hemodynamic forces influence the initiation of atherogenesis. If NF-kappaB plays a role in atherogenesis, then the activation of this signal transduction pathway in arterial endothelium should show topographic variation. The expression of NF-kappaB/IkappaB components and NF-kappaB activation was evaluated by specific antibody staining, en face confocal microscopy, and image analysis of endothelium in regions of mouse proximal aorta with high and low probability (HP and LP) for atherosclerotic lesion development. In control C57BL/6 mice, expression levels of p65, IkappaBalpha, and IkappaBbeta were 5- to 18-fold higher in the HP region, yet NF-kappaB was activated in a minority of endothelial cells. This suggested that NF-kappaB signal transduction was primed for activation in HP regions on encountering an activation stimulus. Lipopolysaccharide treatment or feeding low-density lipoprotein receptor knockout mice an atherogenic diet resulted in NF-kappaB activation and up-regulated expression of NF-kappaB-inducible genes predominantly in HP region endothelium. Preferential regional activation of endothelial NF-kappaB by systemic stimuli, including hypercholesterolemia, may contribute to the localization of atherosclerotic lesions at sites with high steady-state expression levels of NF-kappaB/IkappaB components.

The endothelium in atherogenesis

The focus of this article is an overview of the endothelial changes that initiate and perpetuate the process of atherogenesis. The endothelium can undergo a series of changes which allow it to participate in the inflammatory response; this is known as endothelial cell activation (ECA). The five core changes of ECA are loss of vascular integrity; expression of leucocyte adhesion molecules; change in phenotype from antithrombotic to prothrombotic; cytokine production, and upregulation of HLA molecules. The diverse effects of ECA share a common intracellular control mechanism through the activation of the transcription factors including Nuclear Factor kappaB. ECA is an initiating step in atherogenesis. Modified low density lipoproteins are probably the major cause of endothelial cell activation in atherogenesis, and become especially so after oxidation, glycation (in diabetes) or incorporation in immune complexes. In antiphospholipid syndrome (APS), antiendothelial cell antibodies have been detected in up to 67% of patients. In vitro studies suggest that aPL causes ECA and thus lead to speculation that aPL by causing ECA may initiate atherogenesis. Further clinical and in vitro studies are required to address these issues.

The carboxyl-terminal fragment of alpha1-antitrypsin is present in atherosclerotic plaques and regulates inflammatory transcription factors in primary human monocytes

alpha1-Antitrypsin (AAT) serine proteinase inhibitor is found in most biological fluids, diffuses into most tissues, and is an important factor in controlling tissue damage by proteases in inflammatory diseases such as atherosclerosis. We have previously reported that the C-terminal fragment (C-36) generated during the cleavage of AAT by proteinases forms amyloid fibrils which have biological effects unrelated to precursor functions. Here we show that the C-36 fragment is present in atherosclerotic plaques, particularly within the fibrous cap at the base of the lipid core. We also found that human monocyte stimulation with C-36 fibrils led to a strong activation of both peroxisome proliferator-activated receptors alpha and gamma (PPARalpha and PPARgamma) at 1, 2, and 18 h of cell culture. A parallel increase in the intracellular lipid accumulation was also observed. Furthermore, stimulation of monocytes with C-36 for 18 h led to activator protein-1 (AP-1) and nuclear factor-kappaB (NF-kappaB) activation. These data for the first time demonstrate the peptide of AAT as a component of atherosclerotic plaques and as a novel activator of PPARalpha, PPARgamma, NF-kappaB, and AP-1 in cultured monocytes. Taken together, the effects of the peptide represent a new mechanism of monocyte activation that may be of importance not only in atherogenesis, but also in other inflammatory processes.

Activation of nuclear factor-kB in the spinal cord of experimental allergic encephalomyelitis

The DNA-binding activity of nuclear factor (NF-kB) was found to be induced in the spinal cord of rats with experimental allergic encephalomyelitis (EAE), an animal model of multiple sclerosis (MS), from the onset of the disease. This activation of NF-kB persisted throughout the disease period and decreased thereafter in the recovery phase. Supershift analysis of NF-kB DNA-binding activity in nuclear extracts of spinal cords showed that RelA/p65 and p50 subunits but not c-Rel/p75, RelB/p68 and p52 subunits were involved in DNA binding. Pyrrolidine dithiocarbamate (PDTC), an inhibitor of NF-kB activation, markedly inhibited the in vivo activation of NF-kB in the spinal cord of EAE rats and attenuated the clinical symptoms of EAE. These studies suggest that activation of NF-kB plays an important role in the pathogenesis of EAE and inhibitors of NF-kB activation may have therapeutic importance in MS.

Essential roles of IkappaB kinases alpha and beta in serum- and IL-1-induced human VSMC proliferation

Interleukin-1 (IL-1) is a potent vascular smooth muscle cell (VSMC) mitogen, which can stimulate cells via activation of nuclear factor-kappaB (NF-kappaB) following phosphorylation of its inhibitory subunit (IkappaB). Because the proliferative effect of IL-1 is additive with that of serum, the present studies assessed the role of IkappaB kinases (IKKs) and NF-kappaB in both IL-1- and serum-induced VSMC proliferation. IL-1beta (1 ng/ml) induced marked and persistent NF-kappaB activation in VSMC that was maximal at 1 h and persisted for 3 days. There was a 3-fold increase in DNA synthesis after acute IL-1 exposure (24-96 h) and a 12-fold increase after chronic IL-1 exposure (>7 days). Electrophoretic mobility shift assay and supershift analysis indicated that IL-1-induced NF-kappaB complexes consisted of p65/p50 heterodimers and p50 homodimers. Human saphenous vein smooth muscle cells (HSVSMC) were transiently cotransfected with expression plasmids encoding a dominant negative mutant form of either IKKalpha or IKKbeta, in which K(44) was mutated to A (K44A), and a green fluorescent protein expression plasmid that allows identification of transfected cells. IL-1 induced nuclear localization of p65 in 95% of cells transfected with vector alone but in only 69% and 26% of cells expressing IKKalpha (K44A) or IKKbeta (K44A), respectively. Likewise, proliferation increased 3.2-fold in IL-1-treated HSVSMC which had been transfected with vector alone, but only 2.2- and 1.5-fold proliferation in HSVSMC expressing IKKalpha (K44A) or IKKbeta (K44A), respectively. Although serum activated NF-kappaB transiently, serum-induced proliferation was markedly attenuated in HSVSMC expressing IKKalpha (K44A) and IKKbeta (K44A) compared with HSVSMC transfected with vector alone. The results support an essential role of IKKs in the proliferative response of HSVSMC to IL-1 and to serum.

Antiphospholipid antibodies and the endothelium

This article reviews current understanding of the relationship between antiphospholipid antibodies and the endothelium. In vitro antiphospholipid antibodies produce endothelial cell activation. Clinical data in this area are scanty and worthy of future research, which could lead to new therapies in the management of antiphospholipid syndrome.

Pathogenesis of liver fibrosis: role of oxidative stress

In the liver, the progressive accumulation of connective tissue, a complex and dynamic process termed fibrosis, represents a very frequent event following a repeated or chronic insult of sufficient intensity to trigger a "wound healing"-like reaction. The fibrotic process recognises the involvement of various cells and different factors in bringing about an excessive fibrogenesis with disruption of intercellular contacts and interactions and of extracellular matrix composition. However, Kupffer cells, together with recruited mononuclear cells, and hepatic stellate cells are by far the key-players in liver fibrosis. Their cross-talk is triggered and favoured by a series of chemical mediators, with a prominent role played by the transforming growth factor beta. Both expression and synthesis of this inflammatory and pro-fibrogenic cytokine are mainly modulated through redox-sensitive reactions. Further, involvement of reactive oxygen species and lipid peroxidation products can be clearly demonstrated in other fundamental events of hepatic fibrogenesis, like activation and effects of stellate cells, expression of metalloproteinases and of their specific inhibitors. The important outcome of such findings as regards the pathogenesis of liver fibrosis derives from the observation of a consistent and marked oxidative stress condition in many if not all chronic disease processes affecting hepatic tissue. Hence, reactive oxidant species likely contribute to both onset and progression of fibrosis as induced by alcohol, viruses, iron or copper overload, cholestasis, hepatic blood congestion.

Chlamydia pneumoniae activates nuclear factor kappaB and activator protein 1 in human vascular smooth muscle and induces cellular proliferation

BACKGROUND

Observational data strongly suggest an association between Chlamydia pneumoniae and atherosclerotic cardiovascular disease. However, few studies have mechanistically linked C. pneumoniae to vascular remodeling. The purpose of the present study was to examine the mechanistic relationship between C. pneumoniae and human vascular smooth muscle cell (VSMC) physiology. We sought to determine the influence of human VSMC infection by C. pneumoniae on (1) VSMC proliferation and (2) activation of the proinflammatory and proliferative transcription factors nuclear factor kappaB (NF-kappaB) and activator protein 1 (AP-1).

MATERIALS AND METHODS

C. pneumoniae was grown and isolated from Hep 2 cells. Human aortic VSMCs were inoculated with C. pneumoniae in the presence and absence of the azalide antibiotic azithromycin. Cell proliferation was assayed by direct cell counting 48 h following infection. Two hours following infection, nuclear extracts were isolated, and activation of both NF-kappaB and AP-1 was assessed by electrophoretic mobility shift assay.

RESULTS

Compared with control, C. pneumoniae infection stimulated VSMC proliferation (P < 0.05) and induced both NF-kappaB and AP-1 DNA binding activity. These effects were eliminated by concurrent treatment with azithromycin.

CONCLUSIONS

VSMC infection with C. pneumoniae activates proliferative intracellular signals and stimulates cell growth. These data implicate C. pneumoniae as a pathogenic mediator and a potential therapeutic target in the prevention of atherosclerotic disease.

Induction of signal transduction pathways in rat gastric epithelial cells stimulated with interleukin-1beta

BACKGROUND

Interleukin-1beta (IL-1beta) participates in cell growth, differentiation and apoptosis via activation of several kinases in a variety of cells. Mitogen-activated protein (MAP) kinases are important intermediates of the signal transduction pathway from the cell surface to the nucleus, leading to activation of transcription factors. There are no reports on the effect of IL-1beta on these pathways in gastric epithelial cells.

AIM

To investigate whether IL-1beta activates MAP kinases [extracellular signal-regulated kinases (ERKs), c-Jun NH2-terminal kinases (JNKs) and p38 MAP kinase (p38 MAPK)] and nuclear factor (NF)-kappaB. a transcription factor, in gastric epithelial cells (RGM1).

METHODS

The activities of ERKs and JNKs were estimated by in-gel kinase assay, and p38 MAPK activity was measured by in vitro kinase assay at various time points (0-40 min) after addition of IL-1beta (100 pg/mL) for 20 min. The activity of NF-kappaB was analysed using gel mobility shift assay at times from 0 to 4 h after addition of IL-1beta.

RESULTS

Activity of ERKs was detectable at 10 min, peaked at 20 min, and continued at increased levels until 40 min. Activity of both JNKs and p38 MAPK were detectable during 5-20 min, and then decreased within 40 min. Activation of NF-kappaB occurred at 30 min, and increased activity continued for 6 h. Interleukin-1beta activated MAP kinases and NF-kappaB in RGM1 cells.

CONCLUSION

The activation induced by this cytokine may play an important role in the initiation of the inflammatory process in gastric mucosa.

Macrophages stimulated with IFN-gamma activate NF-kappa B and induce MCP-1 gene expression in primary human endothelial cells

A novel coculture model was established to study the effects of reactive oxygen (ROS) and reactive nitrogen species (RNS) generated by RAW 264.7 macrophages on NF-kappa B activation and monocyte chemoattractant protein (MCP-1) gene expression in primary human endothelial cells (HUVEC). This model simulates free radical-mediated interactions occurring in the process of cardiovascular diseases. The coculture of macrophages grown on filters and stimulated by IFN-gamma-induced a pro-oxidant environment and resulted in increased DNA binding and NF-kappa B transactivation in HUVEC. Activation of NF-kappa B in endothelial cells was accompanied by an evident increase in the expression of the mRNA encoding for the MCP-1 protein, which stimulates the recruitment of monocytes into the arterial wall. Present data suggest that the influx of stimulated monocytes into the subendothelial space could affect redox-sensitive transcription factors and gene expression in the endothelium, thereby possibly leading to endothelial dysfunction.

Nuclear factor-kappa B activity and intestinal inflammation in dextran sulphate sodium (DSS)-induced colitis in mice is suppressed by gliotoxin

In acute DSS-induced colitis nuclear factor (NF)-kappaB-dependent inflammatory cytokines including IL-1 and tumour necrosis factor-alpha (TNF-alpha) are up-regulated. Here we examined the effects of gliotoxin, a fungal metabolite known to inhibit NF-kappaB activity, on cytokine production by a mouse cell system in vitro and on intestinal inflammation and NF-kappaB activation in vivo. In vitro gliotoxin decreased TNF-alpha gene expression and protein production by RAW-264.7 mouse macrophage-like cells stimulated with lipopolysaccharide. In vivo, gliotoxin treatment of mice was begun on day 3 of 5% DSS application dissolved in the drinking water and continued until day 8. Gliotoxin treatment dose-dependently down-regulated colonic inflammation as assessed histologically and in parallel there was a suppression of colonic TNF-alpha and IL-1alpha mRNA expression on day 8 as analysed by semiquantitative reverse transcriptase-polymerase chain reaction (P < 0.01). Furthermore, colonic NF-kappaB DNA-binding activity was increased in DSS-induced colitis and was suppressed by gliotoxin. These results demonstrate the essential role of NF-kappaB in DSS-induced colitis and indicate a molecular approach to the treatment of intestinal inflammatory disorders.

Angiotensin II stimulates endothelial vascular cell adhesion molecule-1 via nuclear factor-kappaB activation induced by intracellular oxidative stress

The recruitment of monocytes via the endothelial expression of vascular cell adhesion molecule-1 (VCAM-1) is a key step in the formation of the initial lesion in atherosclerosis. Because angiotensin (Ang) II may be involved in this process, we investigated its role on the signaling cascade leading to VCAM-1 expression in endothelial cells. Ang II stimulates mRNA and protein expression of VCAM-1 in these cells via the AT(1) receptor. This effect was enhanced by N(G)-nitro-L-arginine methyl ester, a nitric oxide synthase inhibitor, and blocked by pyrrolidinedithiocarbamate, an antioxidant molecule. Ang II activated the redox-sensitive transcription factor nuclear factor-kappaB and stimulated the degradation of both inhibitor of kappaB (IkappaB)alpha and IkappaBbeta with different kinetics. The degradation of IkappaBs induced by Ang II was not modified by incubation with exogenous superoxide dismutase and catalase, suggesting that this effect was not mediated by the extracellular production of O(2)(-). In contrast, rotenone and antimycin, 2 inhibitors of the mitochondrial respiratory chain, inhibited the Ang II-induced IkappaB degradation, showing that generation of reactive oxygen species in the mitochondria is involved on Ang II action. BXT-51702, a glutathione peroxidase mimic, inhibited the effect of Ang II, and aminotriazole, an inhibitor of catalase, enhanced it, suggesting a role for H(2)O(2) in IkappaB degradation. This is confirmed by experiments showing that Ang II stimulates the intracellular production of H(2)O(2) in endothelial cells. These results demonstrate that Ang II induced an intracellular oxidative stress in endothelial cells, which stimulates IkappaB degradation and nuclear factor-kappaB activation. This activation enhances the expression of VCAM-1 and probably other genes involved in the early stages of atherosclerosis.

Increased serum neopterin: a marker of coronary artery disease activity in women

OBJECTIVE

To assess whether neopterin concentrations in women with unstable angina differ from those in women with chronic stable angina.

DESIGN

Prospective cohort study.

SETTING

University hospital in south west London.

PATIENTS

114 consecutive women with angina were studied: 82 had chronic stable angina (typical exertional chest pain, positive exercise ECG testing, and/or abnormal myocardial scintigraphy; symptoms stable for at least three months), and 32 had unstable angina (Braunwald class III). All patients with chronic stable angina (100%) and 18 with unstable angina (56.3%) underwent digital coronary angiography; neopterin concentrations were determined using a commercially available immunoassay.

MAIN OUTCOME MEASURES

Major clinical events during one year follow up were readmission with Braunwald's class IIIb unstable angina, non-fatal myocardial infarction, and cardiac death.

RESULTS

Major events occurred in 12 women with chronic stable angina (14.6%) and nine women with unstable angina (28.1%). Mean (range) neopterin concentrations were significantly higher in women with unstable angina than in those with chronic stable angina (7.6 (5.1-11.5) nmol/l v 5.9 (4.4-7.5) nmol/l; p = 0.003), even after adjustment for variables which were significantly different on univariate analysis. In women with chronic stable angina, baseline neopterin concentrations were higher in those with cardiac events than in those without events (7.1 (5.9-9.1) nmol/l v 5.7 (3.9-7.3 nmol/l); p = 0.010), even after adjustment for variables with significant differences between both groups on univariate analysis.

CONCLUSIONS

On average, women with unstable angina had significantly higher neopterin concentrations than women with chronic stable angina. Women with chronic stable angina with events during follow up had higher neopterin concentrations than those without events. Neopterin concentrations were similar in patients with unstable angina and women with chronic stable angina who developed events. Neopterin concentrations may therefore be a marker of risk in women with coronary artery disease.

Alpha-phenyl-tert-butylnitrone (PBN) inhibits NFkappaB activation offering protection against chemically induced diabetes

Alpha-phenyl-tert-butylnitrone (PBN) is an effective spin trapping agent by reacting with and stabilizing free radical species. Reactive oxygen species (ROS) have been implicated in pancreatic beta cell death and the development of insulin-dependent diabetes mellitus (IDDM). We speculate that treatment with the PBN, will protect against diabetes development in two distinct chemically induced models for IDDM. Pretreatment with PBN (150 mg/kg ip) significantly reduced the severity of hyperglycemia in both alloxan- and streptozotocin (STZ) induced diabetes. To determine the mechanism by which PBN prevents hyperglycemia, we examined the ability of PBN to inhibit NFkappaB activation and to stabilize alloxan- and STZ-induced radicals. Both alloxan and STZ induced NFkappaB activation in the pancreas 30 min after their injection (50 mg/kg iv). PBN pretreatment inhibited both alloxan- and STZ-induced activation of NFkappaB and nitric oxide production. EPR studies showed that PBN could effectively trap alloxan-induced free radicals. It is clear that PBN can inhibit NFkappaB activation in the pancreas and reduce hyperglycemia in two distinct diabetogenic compounds. This research indicates that NFkappaB activation may be a key signal leading to beta cell death and IDDM. Understanding the cellular pathways leading to beta cell death may help in developing effective preventive or therapeutic targets for IDDM.

Angiotensin-converting enzyme inhibitors downregulate tissue factor synthesis in monocytes

Angiotensin-converting enzyme (ACE) inhibitors reduce the risk of recurrent myocardial infarction in patients with left ventricular dysfunction. Tissue factor (TF), the initiator of blood coagulation, plays a pivotal role in arterial thrombosis that occurs after atherosclerotic plaque fissuring. Because monocytes synthesize TF and contain several components of the renin-angiotensin system, we investigated the possibility that ACE inhibitors could modulate monocyte TF expression. Mononuclear leukocytes from healthy volunteers were incubated with endotoxin in the presence or absence of different ACE inhibitors. Captopril reduced TF expression in endotoxin-stimulated mononuclear leukocytes, as measured by a 1-stage clotting assay and ELISA analysis, by approximately 60%. The effect was dose-dependent and was attributable to ACE inhibition, given that other ACE inhibitors, such as idrapril or fosinopril, and losartan, an antagonist of the angiotensin II AT(1) receptor, caused a comparable reduction in TF activity. Reverse transcriptase-polymerase chain reaction indicated that endotoxin-mediated increased levels of TF mRNA were inhibited by ACE inhibitors. Moreover, endotoxin-induced nuclear factor-kappaB translocation to the promoter region of the gene encoding for TF was markedly inhibited by captopril. The finding that ACE inhibitors and angiotensin II AT(1) antagonists can potentially modulate TF expression by mononuclear cells has important biological and therapeutic implications for the evolution of thrombi. Our results suggest that the anti-ischemic effect of these drugs might be explained, at least in part, by their ability to reduce TF expression in monocytes.

Adhesion of monocyte very late antigen-4 to endothelial vascular cell adhesion molecule-1 induces interleukin-1beta-dependent expression of interleukin-6 in endothelial cells

In atheroma, T cell-derived interferon-gamma (INF-gamma) stimulates endothelial cells and facilitates recruitment of monocytes. We investigated potential mechanisms by which these interactions could contribute to local and systemic inflammatory responses. Specifically, we analyzed the expression of interleukin (IL)-1beta and IL-6 in both cell types after coculture, the relevant adhesion molecules in this interaction, and transcriptional control by NF-kappaB. We studied coculture of purified peripheral blood monocytes with human umbilical vein endothelial cells (HUVECs), which were stimulated with INF-gamma (10(6) U/L) to model the activated endothelium of atherosclerotic lesions. Coculture of monocytes with activated HUVECs resulted in release of IL-1beta (40. 6+/-3 pg/24 h, P=0.002) and IL-6 (46.6+/-7 ng/24 h, P=0.0015). Electrophoretic mobility gel shift assay and Northern blotting in each cell type separately revealed NF-kappaB activation in both cell types, IL-1beta mRNA expression predominantly in monocytes, and IL-6 mRNA expression predominantly in HUVECs. The endothelial IL-6 release was IL-1-dependent, because it was suppressed by IL-1 receptor antagonist. Experiments with blocking antibodies demonstrated that binding of monocyte very late antigen-4 (VLA-4) to endothelial vascular cell adhesion molecule-1 (VCAM-1) was necessary for the induction of IL-1beta in monocytes. Binding of monocyte VLA-4 to endothelial VCAM-1 induces NF-kappaB activation in both cell types with expression and release of IL-1beta by monocytes, which in turn stimulates endothelial release of IL-6. The beta(1)-integrin-mediated expression of IL-1beta and IL-6 could contribute to local and systemic inflammatory reactions in atherosclerosis.

Regulation of vascular smooth muscle cell proliferation by nuclear factor-kappaB and its inhibitor, I-kappaB

Proliferation of vascular smooth muscle cells (SMC) is a crucial event in the formation of atherosclerotic tissues and is regulated by nuclear transcriptional factors including nuclear factor-kappaB (NF-kappaB). We constructed a reporter gene assay to measure NF-kappaB-dependent transcriptional activity in SMC. Thrombin receptor-activating peptide (TRAP) and basic fibroblast growth factor (bFGF) stimulated SMC proliferation and rapidly enhanced the NF-kappaB transcriptional activity in a dose-dependent manner. 4-Cyano-5,5-bis-(methoxyphenyl)4-pentenoic acid (E5510) significantly inhibited SMC proliferation and also suppressed NF-kappaB transcription stimulated by TRAP and bFGF. In contrast, although tumor necrosis factor (TNF)-alpha activated NF-kappaB transcription, E5510 had no effect on TNF-alpha-induced activation. NF-kappaB was activated after the stimulation of TRAP, bFGF, and TNF-alpha in electrophoretic mobility shift assay, and E5510 suppressed the NF-kappaB activation induced by TRAP and bFGF but not the activation by TNF-alpha. Western blot analysis of I-kappaBalpha and I-kappaBbeta, inhibitors of NF-kappaB, indicated that I-kappaBalpha degradation, rather than I-kappaBbeta degradation, was important in NF-kappaB activation after the stimulation of TRAP and bFGF. PD98059, an inhibitor of extracellular signal-regulated kinase (ERK) kinase, suppressed NF-kappaB transcriptional activity and SMC proliferation. The phosphorylation of ERK1/2 was rapidly induced by TRAP and bFGF but not by TNF-alpha. These results indicate that TRAP and bFGF induced I-kappaB degradation and NF-kappaB activation through a distinct pathway from TNF-alpha and that ERK1/2 may play an important role in NF-kappaB activation induced by TRAP and bFGF.

Redox regulation of nuclear factor kappa B: therapeutic potential for attenuating inflammatory responses

Nuclear factor kappa B (NF-kappaB) is a protein transcription factor that is required for maximal transcription of a wide array of pro-inflammatory mediators that are involved in the pathogenesis of stroke. The purpose of this review article is to describe what is known about the molecular biology of NF NF-kappaB and to review current understanding of the interaction between reactive oxygen species (ROS) in NF-kappaB. ROS seem to play a duel role by participating in the NF-kappaB activation cascade and by directly modulating DNA binding affinity. Exogenous and endogenous antioxidants are effective in blocking activation of NF-kappaB and preventing the consequences of pro-inflammatory gene expression. Phase II enzymes either directly or indirectly play a major in vivo role in minimizing oxidative stress by scavenging peroxides, peroxide breakdown products and dicarbonyls and in regeneration of lipid peroxidation chain-breaker, vitamin E. Dietary phase II enzyme inducers have been demonstrated to increase phase II enzyme activities in a variety of tissues. These data, together, suggest that phase II enzyme inducers could have therapeutic value for ameliorating inflammatory conditions.

Activated nuclear factor-kappaB is present in the coronary vasculature in experimental hypercholesterolemia

BACKGROUND

Experimental hypercholesterolemia (HC) is characterized by a decrease in nitric oxide (NO) bioavailability and cellular proliferation. Nuclear factor-kappaB (NF-kappaB) is a transcriptional factor which plays a coordinating role in inflammation and cellular proliferation and may be involved in early atherosclerosis. We examined whether activated NF-kappaB was present in experimental hypercholesterolemia in the coronary vasculature in association with a decrease in NO bioavailability.

METHODS

A total of 14 juvenile domestic crossbred pigs were placed on a HC diet and six pigs on a normal diet for 10-12 weeks. A monoclonal antibody to the activated form of the p65 subunit of NF-kappaB was used to detect immunoreactivity in coronary artery sections. Coronary tissue homogenates were analyzed for activated NF-kappaB and endothelial nitric oxide synthase (eNOS) using Western blotting. In vitro coronary endothelium-dependent relaxation was performed in response to bradykinin, as a measure of NO bioavailability.

RESULTS

Intimal staining for activated NF-kappaB was present in 12/14 HC pigs as compared with 0/6 controls (P<0.001). Confocal microscopy confirmed the presence of NF-kappaB in the nucleus of intimal cells although the majority of the staining was cytoplasmic. In the HC group, Western blotting revealed an increase in activated NF-kappaB in the vessel wall compared to the normal group, in association with a decrease in the presence of eNOS protein and an attenuated vasorelaxation response to bradykinin.

CONCLUSION

This study suggests a potential role for activation of NF-kappaB, in association with a decrease in NO bioavailability, in the initial stages of atherosclerosis in the coronary vasculature.

NF-kappaB inhibition ameliorates angiotensin II-induced inflammatory damage in rats

We recently reported that the activation of nuclear factor-kappaB (NF-kappaB) promotes inflammation in rats harboring both human renin and angiotensinogen genes (double-transgenic rats [dTGR]). We tested the hypothesis that the antioxidant pyrrolidine dithiocarbamate (PDTC) inhibits NF-kappaB and ameliorates renal and cardiac end-organ damage. dTGR feature hypertension, severe renal and cardiac damage, and a 40% mortality rate at 7 weeks. Electrophoretic mobility shift assay showed increased NF-kappaB DNA binding activity in hearts and kidneys of dTGR. Chronic PDTC (200 mg/kg SC) treatment decreased blood pressure (162+/-8 versus 190+/-7 mm Hg; P=0.02) in dTGR compared with dTGR controls. The cardiac hypertrophy index was also significantly reduced (4.90+/-0.1 versus 5.77+/-0.1 mg/g; P<0. 001). PDTC reduced 24-hour albuminuria by >95% (2.5+/-0.8 versus 57. 1+/-8.7 mg/d; P<0.001) and prevented death. Vascular injury was ameliorated in small renal and cardiac vessels. Electrophoretic mobility shift assay showed that PDTC inhibited NF-kappaB binding activity in heart and kidney, whereas AP-1 activity in the kidney was not decreased. dTGR exhibited increased left ventricular c-fos and c-jun mRNA expression. PDTC treatment reduced c-fos but not c-jun mRNA. Immunohistochemistry showed increased p65 NF-kappaB subunit expression in the endothelium and smooth muscle cells of damaged small vessels, as well as infiltrating cells in glomeruli, tubules, and collecting ducts of dTGR. PDTC markedly reduced the immunoreactivity of p65. PDTC also prevented the NF-kappaB-dependent transactivation of the intercellular adhesion molecule ICAM-1 and inducible nitric oxide synthase. Monocyte infiltration was markedly increased in dTGR kidneys and hearts. Chronic treatment reduced monocyte/macrophage infiltration by 72% and 64%, respectively. Thus, these results demonstrate that PDTC inhibits NF-kappaB activity, ameliorates inflammation, and protects against angiotensin II-induced end-organ damage.

Cyclosporin A protects against angiotensin II-induced end-organ damage in double transgenic rats harboring human renin and angiotensinogen genes

Leukocyte infiltration and adhesion molecule activation play a central role in the pathogenesis of angiotensin II (Ang II)-induced end-organ damage in double transgenic rats (dTGR) harboring human renin and angiotensinogen genes. We tested the hypothesis that the immunosuppressive agent cyclosporine (CsA) protects against the Ang II-induced myocardial and renal damage in dTGR. Furthermore, we investigated the influence of CsA on interleukin-6 (IL-6) and inducible nitric oxide synthase (iNOS) expression and the DNA binding activity of transcription factor necrosis factor-kappaB (NF-kappaB). The 4-week-old rats were divided into 4 groups: (1) control dTGR (n=20), (2) dTGR plus CsA (5 mg/kg SC for 3 weeks, n=15), (3) normotensive Sprague-Dawley (SD) rats (n=10), and (4) SD rats plus CsA (n=8). In dTGR, CsA completely prevented cardiovascular death (0 of 15 versus 9 of 20), decreased 24-hour albuminuria by 90% and systolic blood pressure by 35 mm Hg, and protected against the development of cardiac hypertrophy. Whole blood CsA concentrations 24 hours after the last drug treatment were 850+/-15 ng/mL. Semiquantitative ED-1 and Ki-67 (a nuclear cell proliferation-associated antigen) scoring showed that CsA prevented perivascular monocyte/macrophage infiltration and prevented cell proliferation in the kidneys and hearts of dTGR, respectively. The beneficial effects of CsA were, at least in part, mediated by the suppression of IL-6 and iNOS expression. Electrophoretic mobility shift assay revealed that CsA regulated inflammatory response in part through the NF-kappaB transcriptional pathway. In contrast to dTGR, CsA increased blood pressure in normotensive SD rats by 10 mm Hg and had no effect on cardiac mass or 24-hour urinary albumin excretion. Perivascular monocyte/macrophage infiltration, IL-6, and iNOS expression or cell proliferation were not affected by CsA in SD rats. Our findings indicate that CsA protects against Ang II-induced end-organ damage and underscore the central role of vascular inflammatory response in the pathogenesis of myocardial and renal damage in dTGR. The beneficial effects of CsA in the kidney and heart are mediated, at least in part, by suppression of IL-6 and iNOS expression via NF-kappaB transcriptional pathway.

Platelets induce alterations of chemotactic and adhesive properties of endothelial cells mediated through an interleukin-1-dependent mechanism. Implications for atherogenesis

Platelets and alterations of chemotactic and adhesive properties of endothelium play an important role in the pathophysiology of atherosclerosis. We investigated the effect of platelets on secretion of monocyte chemotactic protein-1 (MCP-1) and on surface expression of intercellular adhesion molecule-1 (ICAM-1) of cultured endothelium. Pretreatment of cultured monolayers of endothelial cells with alpha-thrombin-activated platelets significantly enhanced secretion of MCP-1 and ICAM-1 surface expression (P<0.01) that could be inhibited by interleukin-1 (IL-1) antagonists by approximately 40%. Activation of transcription factor nuclear factor-kappaB (NF-kappaB) which regulates transcription of early inflammatory response genes such as MCP-1, was significantly increased in endothelial cells treated with activated platelets via an IL-1 mediated mechanism as determined by electrophoretic mobility shift assay (EMSA) and kappaB-dependent transcriptional activity. In trans-well experiments, alpha-thrombin-activated platelets enhanced IL-1-dependent surface expression of vitronectin receptor (alpha(v)beta(3)) on the luminal aspect of endothelial monolayers and promoted alpha(v)beta(3)-mediated platelet/endothelium adhesion that could be inhibited by the antiadhesive peptides GRGDSP and c(RGDfV). We conclude that activated platelets induce significant changes in chemotactic (secretion of MCP-1) and adhesive (surface expression of ICAM-1 and alpha(v)beta(3)) properties of cultured endothelium. These findings imply a potential pathophysiological mechanism of platelets in an early stage of atherogenesis.

Management of oxidative stress in the CNS: the many roles of glutathione

An outline is given of mechanisms that generate oxidative stress and inflammation. Considered are the metabolic mechanisms that give rise to peroxides, the source of strong oxidants; the production of dicarbonyls that interact with macromolecules to form advanced glycation endproducts; and the role that activation of the transcription factor NF(Kappa)B has in the expression of pro-inflammatory genes. Management of oxidative stress is considered by outlining the central role of reduced glutathione (GSH) in peroxide scavenging, dicarbonyl scavenging and activation of NF(Kappa)B. Cellular GSH levels are dictated by the balance between consumption, oxidation of GSH, reduction of oxidized-glutathione, and synthesis. The rate-limiting enzyme in GSH synthesis is L-gamma-glutamyl-L-cysteine synthase, a phase II enzyme. Phase II enzyme inducers are found in many fruits and vegetables. It is suggested that dietary phase II enzyme inducers be investigated for their potential for preventing or retarding the development of degenerative diseases that have an underlying oxidative stress and inflammatory component.

Possible role of proinflammatory cytokines in heart allograft coronary artery disease

Transplant coronary artery disease (Tx-CAD) is the main determinant of long-term prognosis after heart transplantation. Immunologic processes may play a central role in the development of Tx-CAD, but the pathogenesis has not been fully clarified. We examined plasma levels of the proinflammatory cytokines tumor necrosis factor-alpha (TNF-alpha), interleukins (IL)-1beta and IL-6, and the CC-chemokine macrophage chemoattractant protein-1 (MCP-1) in 62 cardiac allograft recipients undergoing yearly heart catherization with coronary angiography for evaluation of graft disease. In this cross-sectional study, we found significantly increased levels of IL-1beta, IL-6, TNF-alpha, and MCP-1 compared with healthy controls even several years (median 7 years) after transplantation in periods with no intercurrent illness. Although no significant differences were found in plasma levels of IL-1beta and TNF-alpha between patients with (n = 25) and without (n = 37) Tx-CAD, the Tx-CAD group had significantly increased levels of IL-6 and MCP-1 compared with both controls and transplant recipients without Tx-CAD. Increased IL-6 levels compared with controls were found only in patients with Tx-CAD. Finally, while there was no significant relation between Tx-CAD and altered lipid status, the combination of high plasma concentrations of IL-6 or MCP-1 and high low-density lipoprotein cholesterol was strongly associated with increased occurrence of Tx-CAD. These findings indicate that cardiac allograft recipients have a persistent immune activation long term after transplantation. This activation, as particularly reflected in increased MCP-1 and IL-6 levels, may be related to the development of Tx-CAD.

Ginkgo biloba inhibits hydrogen peroxide-induced activation of nuclear factor kappa B in vascular endothelial cells

The present study determined the effects of Ginkgo biloba extract (GBE) on the activation of nuclear factor kappa B (NF-kappaB) and the level of hydrogen peroxide (H2O2) in bovine pulmonary artery endothelial cells (PAEC). H2O2 showed a concentration-dependent activation of NF-kappaB. GBE demonstrated a concentration-dependent suppression of NF-kappaB activated by H2O2. GBE directly scavenged H2O2 in a cell-free system; it also decreased H2O2 levels in PAEC. These results suggest that the inhibitory effect of GBE on H2O2-induced NF-kappaB activation may be caused by its scavenging and suppression of H2O2. Our experiments demonstrate that GBE can inhibit NF-kappaB activation induced by H2O2 and may thus be effective for the prevention or treatment of atherosclerosis and other disorders related to NF-kappaB activation.

Role of oxidant stress in cytokine-induced activation of NF-kappaB in human aortic smooth muscle cells

The transcription factor nuclear factor-kappaB (NF-kappaB) has been implicated in inflammatory and proliferative vascular mechanisms. Activated NF-kappaB has been documented in human atherosclerotic lesions, and its activation in human vascular smooth muscle cells (SMC) by cytokines has been reported. However, intracellular mechanisms mediating NF-kappaB activation in human SMC are poorly understood. The aim of this study was to explore the potential role of reactive oxygen species and oxidant stress as signaling events in cytokine-induced NF-kappaB activation. Western blot analysis revealed the presence of inhibitory protein I-kappaBalpha in resting human aortic SMC, which was rapidly phosphorylated and degraded on exposure to interleukin-1beta (IL-1beta) followed by NF-kappaB translocation to the nucleus. IL-1beta had no effect on two measures of intracellular oxidant stress, fluorescence generated by the oxidation of 2',7'-dichlorodihydrofluorescin to dichlorofluorescein (DCF) or changes in intracellular sulfhydryl content. N-acetylcysteine (NAC) a membrane-permeant antioxidant, which augmented intracellular sulfhydryl content and inhibited H(2)O(2)-induced DCF fluorescence, had no effect on cytokine-induced NF-kappaB activation. In contrast to NAC, the metal chelators pyrrolidine dithiocarbamate and diethyldithiocarbamate attenuated IL-1beta-induced NF-kappaB activation but had no effect on intracellular sulfhydryl content. Treatment of the cells with the oxidant H(2)O(2) caused an increase in DCF fluorescence and decreased intracellular sulfhydryl content but had no effect on I-kappaBalpha or NF-kappaB. In conclusion, this study suggests that oxidant stress may not play a major role in cytokine-induced activation of NF-kappaB in human aortic SMC and that oxidants may not be primary activators of NF-kappaB in these cells.

Prolonged activation of NF-kappaB following traumatic brain injury in rats

Activation of transcription factor, nuclear factor kappa B (NF-kappaB), has been shown to play a key role in inflammatory response, neuronal survival and signaling. We investigated the regional and temporal distribution of activated NF-kappaB in rats at 1 h, 2 h, 24 h, 48 h, 1 week, 2 weeks, 1 month, 2 months, 6 months, and 1 year following brain injury in rats. Early after trauma (1-2 h), activated NF-kappaB was detected in axons, and subsequently found in the cytoplasm and nucleus of neurons by 24 h and lasting up to 1 week. In addition, by 24 h posttrauma, activated NF-kappaB was detected in microglia/macrophages and astrocytes in injured cortex. Surprisingly, this activation persisted for at least 1 year following injury in the cortex, primarily at the margins of progressively enlarging ventricle. Activated NF-kappaB was also detected in endothelial cells, as early as 1 h, and persisted for up to 1 year. These results suggest that a neuronal response to brain trauma includes the activation of NF-kappaB first in the axon with subsequent translocation to the nucleus. Furthermore, these results demonstrate that remarkably prolonged activation of NF-kappaB in glia is found in the same regions undergoing persistent atrophy, suggesting NF-kappaB activation may play a role in long-term inflammatory processes following brain trauma.

Nuclear factor kappaB activity is essential for matrix metalloproteinase-1 and -3 upregulation in rabbit dermal fibroblasts

Expression of matrix metalloproteinases (MMPs)-1 and -3 in fibroblasts is upregulated by pro-inflammatory cytokines and growth factors during proliferative inflammatory processes, including wound healing and rheumatoid arthritis. The Activator Protein-1 (AP-1) transcription factor is essential but, we show here, not sufficient for upregulation because platelet derived growth factor (PDGF) and basic fibroblast growth factor (bFGF), which strongly activate AP-1, poorly induce MMP-1 and -3. Interleukin-1alpha, which activates nuclear factor-kappaB (NF-kappaB), synergistically upregulates MMP-1 and -3 expression in the presence of bFGF or PDGF. Adenovirus mediated overexpression of IkappaBalpha, the inhibitor of NF-kappaB, completely suppresses MMP-1 and -3 protein and mRNA expression. Hence, we show for the first time that (NF-kappaB) activity is also essential for MMP-1 and -3 upregulation.

Oxidative stress as a regulator of gene expression in the vasculature

Oxidative stress and the production of intracellular reactive oxygen species (ROS) have been implicated in the pathogenesis of a variety of diseases. In excess, ROS and their byproducts that are capable of causing oxidative damage may be cytotoxic to cells. However, it is now well established that moderate amounts of ROS play a role in signal transduction processes such as cell growth and posttranslational modification of proteins. Oxidants, antioxidants, and other determinants of the intracellular reduction-oxidation (redox) state play an important role in the regulation of gene expression. Recent insights into the etiology and pathogenesis of atherosclerosis suggest that this disease may be viewed as an inflammatory disease linked to an abnormality in oxidation-mediated signals in the vasculature. In this review, we summarize the evidence supporting the notion that oxidative stress and the production of ROS function as physiological regulators of vascular gene expression mediated via specific redox-sensitive signal transduction pathways and transcriptional regulatory networks. Elucidating, at the molecular level, the regulatory processes involved in redox-sensitive vascular gene expression represents a foundation not only for understanding the pathogenesis of atherosclerosis and other inflammatory diseases but also for the development of novel therapeutic treatment strategies.

Intimal deposition of functional von Willebrand factor in atherogenesis

During the formation of intimal thickening in normocholesterolemic rabbits, von Willebrand factor (vWF) is increased in the endothelial cells (ECs) and deposited in the intima. We investigated whether this also occurs during cholesterol-induced plaque formation, whether the synthesis of vWF increases, and whether this influences platelet adhesion. Rabbits were fed a cholesterol-rich (0.3%) diet for 26 weeks. Thereafter, half of the animals received a normal diet for another 26 weeks (cholesterol withdrawal). To induce intimal thickening in normocholesterolemic rabbits, collars were positioned around the carotid artery. Arterial segments were studied using immunohistochemistry, reverse transcription-polymerase chain reaction, electron microscopy, and platelet adhesion tests. Cholesterol treatment induced plaque formation in the aorta. The ECs had a cuboidal aspect, showed a dense immunoreactivity for vWF, a pronounced rough endoplasmic reticulum, and numerous Weibel-Palade bodies. There were subendothelial vWF deposits in the plaques and vWF mRNA was significantly increased as compared with controls. Similar changes were seen after collar-induced intimal thickening. After cholesterol withdrawal, both vWF mRNA and the ultrastructural morphology of the ECs normalized, and the vWF deposits disappeared from the plaque. Perfusion studies with anticoagulated rabbit blood over cross-sections of atherosclerotic aortas revealed increased vWF-mediated platelet adhesion in the subendothelial plaque region. Whereas rabbit platelets perfused through the lumen adhered to the same extent to de-endothelialized aortas of normocholesterolemic and atherosclerotic rabbits, vWF mediated platelet adhesion to endothelium was observed in atherosclerotic but not in normal aortas. Our results show an increased synthesis and (sub)endothelial presence of vWF after vascular injury, with functional consequences for platelet deposition on the vessel wall.

Chlamydia pneumoniae infection of vascular smooth muscle and endothelial cells activates NF-kappaB and induces tissue factor and PAI-1 expression: a potential link to accelerated arteriosclerosis

BACKGROUND

Recent reports link C. pneumoniae infection of arteriosclerotic lesions to the precipitation of acute coronary syndromes, which also feature tissue factor and plasminogen activator inhibitor 1 (PAI-1) overexpression. We investigated whether or not C. pneumoniae can induce thrombogenicity by upregulation of procoagulant proteins.

METHODS AND RESULTS

Human vascular endothelial and smooth muscle cells were infected with a strain of C. pneumoniae isolated from an arteriosclerotic coronary artery. Tissue factor, PAI-1, and interleukin-6 expression was increased in infected cells. Concomitantly, NF-kappaB was activated and IkappaBalpha degraded. p50/p65 heterodimers were identified as the components responsible for the NF-kappaB activity.

CONCLUSIONS

These data provide evidence that C. pneumoniae infection can induce procoagulant protein and proinflammatory cytokine expression. This cellular response is accompanied by activation of NF-kappaB. Our results demonstrate how C. pneumoniae infection may initiate acute coronary syndromes.